Signal processing arrangement



June 5, 1962 c. E. c. ROMIGUIERE 3,038,132

SIGNAL PROCESSING ARRANGEMENT TRANSMITTER TRAN/SMITTER M x EECE/TRANSMITTER ll I TRANSMITTER l I ANTENNA 23 2o TO|2OFFlG.2

FROM ANTENNA A OF FIG.2

TO M OF FIGZ INVENTOR:

6, CLAUDE E.G. ROMIGUIERE, I FROM TRANSMITTER z M 4 b E OF H52 BY HISATTORNEY.

- TO RECEIVER R OFFIGZ United States Patent 3,038,132 SIGNAL PROCESSINGARRANGEMENT Claude Emile Georges Romiguiere, Paris, France, assign or toCompagnie Frangaise Thomson-Houston, Paris,

The present invention concerns improvements to the vane duplexer, also'known as a shutter duplexer. Its basic advantage lies in the moreefiicient protection of the receiver.

The vane duplexer possesses the advantage over similar previously knowndevices such as those containing resonant gas cells (known as TR tubes)of being usable at very high transmission powers, i.e., of megawattpower without reduction in performance or destruction. Howeverq, the useof this better duplexer is limited by the fact that the power, whichreaches the receiver in stationary transmission operations, calledleakage-power is dangerous for the receiver, particularly for itsdetection crystal.

From the viewpoint of protection of the receiver, the most efficientduplexer has hitherto been the twin TR tube type, more commonly known asthe double TR duplexer. FIG. 1 shows its working principle. It consistsof two 3 db directional couplers 1 and 2 and two TR tubes 3 and 4. Thepower P from a source of electromagnetic waves such as a transmitter Eis divided by the coupler 1 into two equalparts, P1 and P2 which arereflected into the fired tubes 3 and 4. The two reflected powerstreamsP3 and P4 travel towards a first load circuit, such as an antenna A, thestreams P5 and P6 entering the transmitter line cancelling one another.The leakage-power fiows P7 and P8 are conveyed, at the coupler 2 output,by reason of the geometry of the system, to a second load circuit suchas a power absorption resistance 5. The power-flows entering the linetowards a third load circuit, such as a receiver R cancel themselvesalmost entirely. It is this shunting of the leakage-powers whichexplains the excellent protection of the receiver which the duplexer canachieve. Unfortunately, this duplexer is not suitable for use at thehigh powers which can be tolerated by the vane duplexer. The attempthas, therefore, been made to discover devices which incorporate theefficiency of the vane duplexer.

The efiiciency of the vane duplexer could be improved by connecting itto a receiver through a TR tube of known type which fires under theaction of the leakage-power of the vane duplexer. The finalleakage-power in such a case does not exceed the level to be found inmediumpower transmitter-receiver units equipped with TR tubes only.However, this solution is not always satisfactory since the specificleakageapower of the live TR tube may still be dangerous for thereceiver.

Another solution would be to couple in series a TR tube and a vaneduplexer. by the association of two single vane duplexers and cantolerate twice the power of a single duplexer. Moreover, it protects thereceiver more efiiciently since it incorporates a system ofleakage-power shunting similar to that of the twin-TR tube duplexer.But, by asso This duplexer is obtained ciating a duplexer of this modelwith a TR tube, the protection of the receiver is not necessarilyincreased. Two possibilities may arise: Either the TR tube may fireunder the action of the duplexer leakage-power and deliver its specificleakage power, which is fairly high, to the receiver, or the vaneduplexer leakage-power may be too low to fire the TR tube, while stillbeing dangerous to the receiver.

The subject of the present invention is a duplexer which affords highlyeffective protection to the receiver without any of the disadvantagesmentioned above. The new device is obtained by introducing a TR tubeinto each of two guides located between a 3 db directional coupler andtwo all-pass couplers. It may also be regarded as resulting from thecombination of a duplexer first arrangement and of a second arrangementinvolving a double TR tube duplexer. This combination is not simply amatter of mere series connection, but results from suitable coupling ofthe two duplexers in such a way that the two leakagepower fluxes fromthe double vane duplexer are conveyed to the two TR tubes. The latterthereupon fires correctly, since contrary to the series coupling of thedouble vane duplexer and a TR tube there is no splitting of theleakage-power between the vane duplexer and the TR tubes. Finally, thenew duplexer is a compact and relatively simple structure.

Briefly, in accordance with one embodiment of my invention there isprovided a combination of first, second, third and fourth waveguides, asource of electromagnetic waves, a first, second, third, fourth, fifth,sixth and seventh load circuits, wherein said third circuit comprises anantenna, said fourth circuit comprises a wave receiver, and said second,fifth, sixth and seventh circuits comprise wave absorbing resistances, afirst, second and third 3 db directional couplers, and a first andsecond TR device, and a first and second directional couplers. Saidcouplers comprise an ionizable medium which is normally non-ionized.Said source is coupled to one end of said first guide, said first loadcircuit coupled to the other end of said first guide, and said secondand third circuits are coupled to respective ends of said second guide.Said first and second 3 db couplers couple said first and second guidesthrough common waveguide wall connections at respective spaced-apartfirst and second points along said first and second guides. Said fourthand fifth circuits are coupled to respective ends of said third guideand said sixth and seventh circuits are coupled to respective ends ofsaid fourth guide. Said first and second 100% directional couplerscouple said first and third guides and said second and fourth guides,respectively, through common waveguide wall connections at respectivethird and fourth points located between said first and second points.Said TR devices are mounted within respective ones of said third andfourth guides and positioned between said fourth circuit and said first100% directional coupler and between said sixth circuit and said second100% directional coupler respectively. Said third 3 db coupler couplessaid third and fourth guides through a common waveguide wall connectionat a point between said TR devices and said fourth and sixth circuits.In order to propagate waves from said source to said third circuitthrough said first and second 3 db couplers, said first and second 100%directional couplers are made responsive to the intensity of waves abovea predetermined level received from said source by way of propagationthrough said first and second waveguides and said first 3 db coupler forbecoming ionized such that a negligible amount of such waves can reachthe fourth circuit. In order to propagate Waves from said third circuitto said fourth circuit, said first and second 100% directional couplersare adapted to be nonionized for coupling said last-named waves throughsaid TR devices, said third and fourth waveguides and said third 3 dbcoupler to said fourth circuit.

While the novel and distinctive features of the invention areparticularly pointed out in the appended claims, a more expositorytreatment of the invention, in principle and in detail, together withadditional objects and advantages thereof, is afforded by the followingdescription and accompanying drawings in which:

FIG, 1 shows a prior art twin TR tube type duplexer;

FIG. 2 shows the basic diagram of the duplexer;

FIG. 3 shows the distribution of the power flux during transmission ofelectromagnetic waves;

FIG. 4 is the diagram of power distribution when receivingelectromagnetic Waves; and

FIG. 5 is a further embodiment of the present invention.

Referring to FIG. 2, it will be seen that the duplexer consists of fourguides 6, 7, 8 and 9. Guides 6 and 7 are connected respectively to thetransmitter E and the antenna A and terminates in matched resistances 1tand 11. Guide 8 is connected to the receiver R and also terminates atmatched resistance 12. Guide 9 likewise terminates at the two matchedresistances 13 and 14. TR tubes 15 and 16 are inserted in guides 8 and9.

Coupling between the guides is efiected as follows: Two 3 db directionalcouplers 17 and 18 couple guide 6 with guide 7; all-pass directionalcouplers '19 and 20 located in guides 6 and 7 between couplers 17 and 18couple guide 6 with guide 8 on one hand and guide 7 with guide 9 on theother. In the slots of the all-pass couplers an ionizable medium in theform of a series of gas tubes 21 and 22 is located. Finally, the 3 dbdirectional coupler couples guide 8 with guide 9 at a place separatedfrom couplers 19 and 20 by tubes 15 and 16.

On stationary transmission operation during the flat stretch of thetransmitted pulse when all the gas tubes 15, 16, 21, 22 are live, thetransmission power, the path of which is shown by the dotted line 24, isdivided by the coupler 17 into two fluxes 25 and 26 as shown in FIG. 3.The latter, reduced by leakage-power and losses occurring at the levelof couplers 19 and 20 are both conveyed by coupler 18 towards theantenna A. Fluxes 27 and 28 conveyed towards resistance 10 cancel eachother out almost entirely. The leakage-power, entering by 19 and 20 inguides 8 and 9, are for the most part (fluxes 29 and 30) absorbeddirectly by resistances 12 and 14. The residual power fluxes (31 and 32)travel towards the TR tubes 15 and 16 where they are for the most part(fluxes 33 and 34) reflected towards resistances 12 and 14.Consequently, the TR tubes 15 and 16 are traversed by very low fluxes 35and 36 which on account of their phase relation are conveyed by coupler23 toward resistance 13, fluxes 37 and 38 conveyed towards resistance 13virtually cancelling each other.

On stationary receiving operation, where no gas tube is live, the powerfrom antenna A is divided by coupler 18 into two fluxes 40 and 41 asshown in FIG. 4. The latter almost entirely enter the guides 8 and 9respectively, pass through TR tubes 15 and 16 and are conveyed bycoupler 23 almost in their entirety towards the receiver R.

FIG. 2 represents a particular arrangement in which the guide axes areall in the same plane. Other arrangements are possible with a differentgeometry from FIG. 2 without departing from the spirit of the invention.

FIG. 5 shows a partly cut-away perspective view of such a duplexer, thestructure of which consists of four guides assembled in pairs, eithernarrow side to narrow side or broad side to broad side. The couplingslots of the 3 db duplexers 17, 18, 23 are cut into the broader sideswhile the through couplers 19 and 20 which are equipped with gas tubesare located along the narrow sides. In the structure at FIG. 5, guides 6and 7 have the broader sidewalls in common, likewise guides 8 and 9,while guides 6 and 8 together with guides 7 and 9 have their narrowsidewalls in common. This structure also makes possible simplificationof construction and maintenance. The apertures of all-pass couplers 19and 20 can be arranged one beside the other, which then enables only oneset of gas tubes 42 to be used for these two apertures.

While the principles of the invention have now been made clear, therewill be immediately obvious to those skilled in the art manymodifications in structure, arrangement, proportions, the elements andcomponents used in the practice of the invention, and otherwise, whichare particularly adapted for specific environments and operatingrequirements without departing from those principles. The appendedclaims are therefore intended to cover and embrace any suchmodifications within the limits of the true spirit and scope of theinvention.

What I claim and desire to secure by Letters Patent of the United Statesis:

1. A duplexer comprising first, second, third and fourth rectangularwaveguides, a source of electromagnetic waves coupled to one end and afirst wave absorbing means coupled to the other end of said first guide,a receiver coupled to one end and a second wave absorbing means coupledto the other end of said second guide, an antenna coupled to one end anda third wave absorbing means coupled to the other end of said fourthguide, fourth and fifth wave absorbing means coupled, respectively, toopposing ends of said third guide, said first and second guide beingcontiguous and having a first common wall portion, said third and fourthguide being contiguous and having a second common wall portion, saidfirst common wall portion including a first long slot directionalcoupler, said second common wall portion including a second long slot100% directional coupler, said first and second directional coupler eachcomprising a plurality of ionizable gas tubes oriented in the plane ofthe wall portion and extending transversely to the longitudinal axis ofthe guide, a first and a second 3 db coupler coupling said first andfourth guides on opposite sides of said directional coupler,respectively, said second and third guides being contiguous and having athird common wall portion, a third 3 db directional coupler located insaid third common wall portion at a point in said second waveguideintermediate said end coupled to the receiver and the directionalcoupler, a first TR tube in said second guide and a second TR tube insaid third guide, each of said TR tubes located at a point along thelongitudinal guide axis intermediate said third 3 db coupler and saiddirectional couplers.

2. A duplexer comprising first, second, third and fourth rectangularwaveguides, a source of electromagnetic waves coupled to one end and afirst Wave absorbing means coupled to the other end of said first guide,a receiver coupled to one end and a second wave absorbing means coupledto the other end of said second guide, an antenna coupled to one end anda third wave absorbing means coupled to the other end of said fourthguide, fourth and fifth wave absorbing means coupled, respectively, toopposing ends of said third guides, respectively, said first and secondguide being contiguous and having a first common narrow wall portion,said third and fourth guide being contiguous and having a second commonnarrow wall portion, said first common narrow wall portion including afirst long slot 100% directional coupler, said second narrow common wallportion including a second long slot 100% directional coupler, saidfirst and second directional coupler each comprising a plurality ofionizable gas tubes oriented in the plane of the wall portion andextending transversely to the longitudinal axis of the coupled to thereceiver and the directional coupler, a first 10 2,945,194

TR tube in said second guide and a second TR tube in said third guide,each of said TR tubes located at a point along the longitudinal guideaxis intermediate said third 3 db coupler and said directional couplers.

References Cited in the file of this patent UNITED STATES PATENTS SannerOct. 20, 1959 Reverdin July 12, 1960

